1. Field of the Invention
The present invention relates to an imaging apparatus and a solid-state imaging device thereof, and particularly relates to an imaging apparatus and a solid-state imaging device thereof capable of performing focus control.
2. Description of the Related Art
In recent years, imaging apparatuses capable of taking and storing images by using a solid-state imaging device such as a digital still camera and a digital video camera are widely used. As an imaging device used for such imaging apparatuses, a CCD image sensor has been most commonly used, however, a CMOS image sensor is receiving attention as the number of pixels of the imaging device is further increased. The CMOS image sensor has advantages that the sensor can randomly access pixel signals and perform readout at high speed, furthermore, it is highly sensitive and has low power consumption as compared with the CCD image sensor.
Incidentally, in this type of imaging apparatus, an autofocus (AF) function which automatically focuses on a subject is commonly mounted (for example, refer to JP-A-2004-289870. Imaging conditions of focus are adjusted based on image signals outputted from the solid-state imaging device. For example, high luminance components of image signals are integrated to calculate a focus evaluation value, and the position of a focus adjustment lens is adjusted so that the focus evaluation value becomes maximum.
FIG. 11 shows a configuration of an imaging apparatus of related art. The imaging apparatus 100 in related art includes a solid-state imaging device 101, a DSP 102, an edge detection unit 103, a focus evaluation value generating unit 104, a control unit 105, a focus adjustment lens 106, a lens moving mechanism 107, a diaphragm 108, a diaphragm drive unit 109 and so on.
When performing autofocus control, the control unit 105 allows the solid-state imaging device 101 to output image signals, inputting the image signals to the DSP 102 through an interface (I/F). The DSP 102 generates image luminance signals from the image signals and outputs the signals to the edge detection unit 103. The edge detection unit 103 extracts high-frequency components of the image luminance signals (hereinafter, refer to “high luminance components” in the following description) and detects an edge portion of a taken image from the high luminance components to output to the control unit 105. The control unit 105 confines a focus area to the periphery of the edge portion based on the information acquired from the edge detection unit 103.
The control unit 105 controls the solid-state imaging device 101 to output image signals in the focus area from the solid-state imaging device 101 as well as outputs high luminance components to the focus evaluation value generating unit 104 through the I/F, the DSP 102 and the edge detection unit 103. The focus evaluation value generating unit 104 outputs a value obtained by integrating the high frequency components to the control unit 105 as a focus evaluation value. The control unit 105 controls the lens moving mechanism 107 to move the focus adjustment lens 106 and performs the same processing to determine the position of the focus adjustment lens 106 at which the focus evaluation value becomes maximum as a focused position, then, the control unit 105 arranges the focus adjustment lens 106 at the focused position.